This invention relates generally to lid handling systems. Lids are typically received from production facilities in a randomly oriented manner and are destined for use in the medical, food service, and toy industries. It is therefore necessary that these lids be single-filed, oriented, stacked, counted, and placed into a carton for shipping without disturbing the counted stacks. Single-filing, orienting, and stacking operations have been automated in the prior art. However, these prior art systems are limited in terms of the number of lids per minute that can be handled. Today's high speed production operations require higher lid handling rates. Manually counting and placing lids into a carton is labor intensive and also slow.
Single-filing of the lids has commonly been accomplished by using the centrifugal force of a horizontally positioned rotary disc to first move lids to the outside circumference of the disc. A single, flat lid may then exit the disc through a slot that is the same height as the lid. Lids that are positioned on top of each other can occasionally jam in the slot and completely stop production. Even if a jam does not occur, two lids attempting to exit the slot together tend to hesitate before moving downstream from the slot. This situation can dramatically reduce the throughput of the lid handling system.
Additionally, lids must be channeled into one or more lanes. After exiting the slot, existing systems use a stationary guide to route the lids into one or more lanes. Lids that do not directly enter a lane, but instead impact the stationary guide, can cause stoppages or hesitation in the flow of lids.
After being routed into lanes, lids must be stacked horizontally and separated into counted stacks. Stacking has historically been accomplished by utilizing horizontal spin bars. The difficulty of separating lids into a counted, horizontal stack arises because the lids are spinning, and variations in the lids can change the location of the seam between adjacent lids. Sweep motion devices have been used in the past to accomplish lid separation. These devices typically do not reliably locate the seam in the stacks of lids, thus disturbing the stacks and frequently knocking some lids off the horizontal spin bars.
After lids are counted into stacks, the stacks must then be moved without disturbing their alignment in order to place them into a carton. This is difficult because lids frequently fit together with an interference of only a few thousandths of an inch. If the integrity of the stack is not maintained, individual lids may warp during shipment, rendering them unusable. No method has yet been devised to move stacks of lids reliably. The prior art method of handling stacks of lids is to manually place them into a carton. Placing a counted stack directly into a carton is difficult because the carton tolerance must be tight to maintain stack alignment during shipping. Frequently, a plastic liner placed in the carton snags lids that are located on the ends of each stack, thereby resulting in mis-alignment of the stack. When one layer of stacked lids is placed into a carton, a piece of cardboard is manually placed over that layer of lids, and another layer of stacked lids is added. This process is repeated until the carton is filled, but since each stack must be handled manually, labor costs are high, and the potential for contamination exists.
It is therefore the principal object of the present invention to provide an improved lid handling system having increased output, while reducing stoppage and labor costs.
This and other objects are accomplished in accordance with the illustrated preferred embodiment of the present invention by providing a lid alignment assembly, a lid separation assembly, and a vacuum pickup assembly.
The lid alignment assembly of the present invention eliminates stoppages at the input end of the system by replacing the traditional lid exit slot with a horizontally positioned moving belt located one lid height above a horizontal rotating disc. Any lids positioned on top of each other will contact the moving belt and be moved by the belt away from the lid exit slot.
After lids exit the rotating disc through the lid exit slot, a secondary stoppage can occur when lids impact a stationary guide that defines the single lane at the output of the rotating disc. This stoppage problem is eliminated in accordance with the present invention by locating a rotating wheel at the impact point of the stationary guide. This wheel will force each lid to either move into the output lane or back onto the rotating disc to be recycled.
Separating lids into counted stacks without knocking off the conventional rotating spin bars is accomplished by replacing prior art separating devices with a beveled separating wheel that is mounted for free wheeling and sliding movement on a shaft. When the separating wheel is lowered into contact with a stack of spinning lids, it will in turn begin to spin with a circumferential speed equal to that of the lids. If the shaft on which the separating wheel is mounted is angled both upwards and sideways with respect to the stack of lids, the separating wheel will be forced to move parallel to the stack of lids until it contacts a seam between two lids. This will allow an accurate separation into stacks of a desired length without knocking lids off of the spin bars.
Transporting counted stacks of lids is accomplished by lifting each stack from above using the vacuum pickup assembly that has length and width dimensions approximately equal to the stacks of lids. The vacuum pickup assembly is arranged to be mechanically lowered into near contact with the spinning stacks of lids. Vacuum ports on the underside of the vacuum pickup assembly serve to lift the spinning stacks of lids into associated stack receivers. A flexible, low-friction fabric material attached to each of the stack receivers serves to seal the vacuum without disturbing the stacks of lids. The result is that the stacks of lids will be pulled upward off the spin bars and the spinning stopped without disturbing lid alignment. Since the peripheral edge of each lid is firmly held by vacuum, the stacks of lids can then be transported without disrupting the lid alignment.
Lid handling labor and the opportunity for contamination can be reduced by automatically placing the stacks of lids onto a holding tray that can retain an entire layer of stacks of lids. The bottom of each tray serves as a divider between layers when placed into the carton. Each tray includes an upwardly bent flap on each end that contacts, holds, and protects the end lids of each stack. An additional problem that is overcome by the present invention exists when the number of stacks of lids that are transported by the vacuum pickup assembly is not the same number required to fill each tray. By placing trays adjacent to each other, the vacuum pickup assembly places the stacks of lids into trays as required. While conveying a filled tray, an external guide holds the end flaps in position to provide pressure on each stack, thereby maintaining stack alignment. The entire tray can then be placed into a carton, either manually or automatically. In either instance, labor is reduced, stack alignment is maintained by protecting the end lids of each stack from the plastic carton liner, and potential contamination is reduced by eliminating manual handling of each individual stack of lids.